The present invention relates to guided projectiles and, more particularly, to guided gun-launched projectiles having steering canards for developing aerodynamic lift resulting in improved circular error probabilities (CEPs).
One method of improving precision of gun-launched munitions is to incorporate a target seeker therein with appropriate electronics for developing control signals and providing means for developing aerodynamic lift to correct errors in the flight path. Such means for developing aerodynamic lift can include one or more canards in a guidance assembly which are preferably maintained in the neutral position during launch and are later controlled according to the guidance signals.
Conventional projectiles typically spin at relatively high spin rates imparted by rifling in the barrel.
In order to properly absorb launch acceleration, it is necessary to permit rigid mechanical coupling between the portion of the guidance assembly carrying the canards and the remainder of the projectile body. After launch, it is desirable to despin the portion of the guidance assembly including the canards until they are substantially roll stationary in geocentric coordinates. Sensor outputs may thereupon be used to roll the plane in which aerodynamic lift may be exerted and control signals may thereupon be used to deflect deflectable canards as required to produce aerodynamic lift in that plane.
It is desirable to prevent premature deflection of the deflectable canards until the canards are despun. One method of preventing such deflection includes the friction of a reduction gearing device in the canard drive. However, unbalance of inertias of the reduction gearing device or the remainder of the drive train may permit the movable canards to deflect prematurely.